\(\frac{s}{2\cdot v2}+\frac{s}{v2}=\frac{1}{4}\)
\(\frac{s}{v2}\left(\frac{1}{2}+1\right)=\frac{1}{4}\)
\(\frac{s}{v2}\cdot\frac{3}{2}=\frac{1}{4}\)
\(\frac{s}{v2}=\frac{1}{4}:\frac{3}{2}=\frac{1}{6}\)
với s=3,6
\(\Rightarrow\frac{18}{5}:v2=\frac{1}{6}\)
\(\Rightarrow v2=\frac{18}{5}:\frac{1}{6}=21,6\)